lua-calendrica

# Module `calendrica-hebrew`

Hebrew calendar conversions and holidays.

Ported from "Calendrical Calculations" (4th edition) by Nachum Dershowitz and Edward M. Reingold. Original Lisp code (CALENDRICA 4.0) is Apache 2.0 licensed.

### Info:

- Release: 0.1 2026-07-19

## Functions

hebrew_date (year, month, day) | Construct a Hebrew date {year, month, day}.
fixed_from_hebrew (h_date) | Fixed date of Hebrew date `h_date`.
hebrew_from_fixed (date) | Hebrew date {year, month, day} corresponding to fixed `date`.
yom_kippur (g_year) | Fixed date of Yom Kippur occurring in Gregorian year `g_year`.
rosh_hashanah (g_year) | Fixed dates of Rosh Hashanah (Hebrew New Year, Tishri 1) in Gregorian year `g_year`.
sukkot (g_year) | Fixed dates of Sukkot (Tishri 15) in Gregorian year `g_year`.
shavuot (g_year) | Fixed dates of Shavuot (Sivan 6) in Gregorian year `g_year`.
passover (g_year) | Fixed date of Passover occurring in Gregorian year `g_year`.
purim (g_year) | Fixed date of Purim occurring in Gregorian year `g_year`.
ta_anit_esther (g_year) | Fixed date of Ta'anit Esther occurring in Gregorian year `g_year`.
tishah_be_av (g_year) | Fixed date of Tishah be-Av occurring in Gregorian year `g_year`.
hanukkah (g_year) | Fixed dates of Hanukkah (first day) occurring in Gregorian year `g_year`.
yom_ha_zikkaron (g_year) | Fixed date of Yom ha-Zikkaron occurring in Gregorian year `g_year`.
hebrew_in_gregorian (h_month, h_day, g_year) | Fixed dates of Hebrew month/day `h_month`/`h_day` falling in Gregorian year `g_year`.
hebrew_leap_year (h_year) | True if `h_year` is a Hebrew leap year.
hebrew_sabbatical_year (h_year) | True if `h_year` is a Hebrew sabbatical (shmita) year.
omer (date) | Day of the Omer for fixed `date` (1..49), or BOGUS outside the Omer period.
birkath_ha_hama (g_year) | Fixed dates of Birkath HaHama in Gregorian year `g_year`.
sh_ela (g_year) | Fixed dates of Sh'ela (prayer for rain) in Gregorian year `g_year`.
hebrew_birthday_in_gregorian (birthdate, g_year) | Fixed dates of Hebrew `birthdate` anniversary falling in Gregorian year `g_year`.
yahrzeit_in_gregorian (death_date, g_year) | Fixed dates of yahrzeit for Hebrew `death_date` falling in Gregorian year `g_year`.

## Fields

NISAN | Nisan month number (1).
IYYAR | Iyyar month number (2).
SIVAN | Sivan month number (3).
TAMMUZ | Tammuz month number (4).
AV | Av month number (5).
ELUL | Elul month number (6).
TISHRI | Tishri month number (7).
MARHESHVAN | Marheshvan month number (8).
KISLEV | Kislev month number (9).
TEVET | Tevet month number (10).
SHEVAT | Shevat month number (11).
ADAR | Adar month number (12).
ADARII | Adar II month number (13, leap years only).

## Functions

hebrew_date (year, month, day)
  Construct a Hebrew date {year, month, day}.

  ### Parameters:

  - year number Hebrew year.
  - month number Hebrew month.
  - day number Hebrew day.

  ### Returns:

  table {year, month, day}
fixed_from_hebrew (h_date)
  Fixed date of Hebrew date `h_date`.

  ### Parameters:

  - h_date table Hebrew date {year, month, day}.

  ### Returns:

  number Fixed date.
hebrew_from_fixed (date)
  Hebrew date {year, month, day} corresponding to fixed `date`.

  ### Parameters:

  - date number Fixed date.

  ### Returns:

  table {year, month, day}
yom_kippur (g_year)
  Fixed date of Yom Kippur occurring in Gregorian year `g_year`.

  ### Parameters:

  - g_year number Gregorian year.

  ### Returns:

  number Fixed date.
rosh_hashanah (g_year)
  Fixed dates of Rosh Hashanah (Hebrew New Year, Tishri 1) in Gregorian year `g_year`.

  ### Parameters:

  - g_year number Gregorian year.

  ### Returns:

  {number,...} Fixed dates.
sukkot (g_year)
  Fixed dates of Sukkot (Tishri 15) in Gregorian year `g_year`.

  ### Parameters:

  - g_year number Gregorian year.

  ### Returns:

  {number,...} Fixed dates.
shavuot (g_year)
  Fixed dates of Shavuot (Sivan 6) in Gregorian year `g_year`.

  ### Parameters:

  - g_year number Gregorian year.

  ### Returns:

  {number,...} Fixed dates.
passover (g_year)
  Fixed date of Passover occurring in Gregorian year `g_year`.

  ### Parameters:

  - g_year number Gregorian year.

  ### Returns:

  number Fixed date.
purim (g_year)
  Fixed date of Purim occurring in Gregorian year `g_year`.

  ### Parameters:

  - g_year number Gregorian year.

  ### Returns:

  number Fixed date.
ta_anit_esther (g_year)
  Fixed date of Ta'anit Esther occurring in Gregorian year `g_year`. If Purim is on Sunday, returns the prior Thursday; otherwise the day before.

  ### Parameters:

  - g_year number Gregorian year.

  ### Returns:

  number Fixed date.
tishah_be_av (g_year)
  Fixed date of Tishah be-Av occurring in Gregorian year `g_year`. If the ninth of Av is Saturday, returns the next day.

  ### Parameters:

  - g_year number Gregorian year.

  ### Returns:

  number Fixed date.
hanukkah (g_year)
  Fixed dates of Hanukkah (first day) occurring in Gregorian year `g_year`.

  ### Parameters:

  - g_year number Gregorian year.

  ### Returns:

  table List of fixed dates.
yom_ha_zikkaron (g_year)
  Fixed date of Yom ha-Zikkaron occurring in Gregorian year `g_year`. Observance is moved if Iyyar 4 falls on Thursday, Friday, or Sunday.

  ### Parameters:

  - g_year number Gregorian year.

  ### Returns:

  number Fixed date.
hebrew_in_gregorian (h_month, h_day, g_year)
  Fixed dates of Hebrew month/day `h_month`/`h_day` falling in Gregorian year `g_year`.

  ### Parameters:

  - h_month number Hebrew month.
  - h_day number Hebrew day.
  - g_year number Gregorian year.

  ### Returns:

  {number,...} Fixed dates.
hebrew_leap_year (h_year)
  True if `h_year` is a Hebrew leap year.

  ### Parameters:

  - h_year number Hebrew year.

  ### Returns:

  boolean
hebrew_sabbatical_year (h_year)
  True if `h_year` is a Hebrew sabbatical (shmita) year.

  ### Parameters:

  - h_year number Hebrew year.

  ### Returns:

  boolean
omer (date)
  Day of the Omer for fixed `date` (1..49), or BOGUS outside the Omer period. Returns {weeks, days} where weeks is complete weeks and days is remaining days.

  ### Parameters:

  - date number Fixed date.

  ### Returns:

  table or number {weeks, days} or BOGUS.
birkath_ha_hama (g_year)
  Fixed dates of Birkath HaHama in Gregorian year `g_year`. Occurs when Nisan 1 falls on Wednesday in a year divisible by 28 (solar cycle).

  ### Parameters:

  - g_year number Gregorian year.

  ### Returns:

  {number,...} Fixed dates (empty if not occurring this year).
sh_ela (g_year)
  Fixed dates of Sh'ela (prayer for rain) in Gregorian year `g_year`.

  ### Parameters:

  - g_year number Gregorian year.

  ### Returns:

  {number,...} Fixed dates.
hebrew_birthday_in_gregorian (birthdate, g_year)
  Fixed dates of Hebrew `birthdate` anniversary falling in Gregorian year `g_year`.

  ### Parameters:

  - birthdate table Hebrew date {year, month, day}.
  - g_year number Gregorian year.

  ### Returns:

  {number,...} Fixed dates.
yahrzeit_in_gregorian (death_date, g_year)
  Fixed dates of yahrzeit for Hebrew `death_date` falling in Gregorian year `g_year`.

  ### Parameters:

  - death_date table Hebrew date {year, month, day}.
  - g_year number Gregorian year.

  ### Returns:

  {number,...} Fixed dates.

## Fields

NISAN
  Nisan month number (1).
IYYAR
  Iyyar month number (2).
SIVAN
  Sivan month number (3).
TAMMUZ
  Tammuz month number (4).
AV
  Av month number (5).
ELUL
  Elul month number (6).
TISHRI
  Tishri month number (7).
MARHESHVAN
  Marheshvan month number (8).
KISLEV
  Kislev month number (9).
TEVET
  Tevet month number (10).
SHEVAT
  Shevat month number (11).
ADAR
  Adar month number (12).
ADARII
  Adar II month number (13, leap years only).

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